Most small businesses that have a network with internet access also have email accounts for  their users. Depending upon the type of network you are running, you can have either a POP3 email system or a Simple Mail Transfer Protocol (SMTP) server based system.

E-mail Name Resolution

When configuring Internet e-mail, it is important to understand how e-mail names are resolved. For an SMTP-based mail server to receive e-mail from another SMTP-based mail server (such as your ISP mail server) you must have a registered e-mail Internet domain name, such as capdata.com. You must also request that your ISP create a DNS mail exchange (MX) resource record and a DNS address (A) resource record for the server. SMTP relies on DNS MX records to direct e-mail for a particular domain name to the correct destination.

POP3

Post Office Protocol 3 (POP3) is a messaging protocol commonly used to receive personal e-mail through an Internet service provider (ISP). When e-mail messages are sent to an individual with a POP3 mailbox, the messages reside on the mail server until the individual retrieves them using a POP3 e-mail client.

Because POP3 is a messaging protocol designed for retrieval only, it must work in conjunction with a protocol capable of sending messages, such as SMTP.

Limitations of POP3 e-mail include:

• Messages are not received in real time.
• After messages are downloaded, they are deleted from the server.
• Downloaded messages are stored on the local client computer.

SMTP Server Based

Simple Mail Transfer Protocol (SMTP) is the standard protocol for transferring e-mail from server to server over the Internet. It defines how a message is formatted for delivery and also provides the delivery mechanism over connection-based protocols, such as Transmission Control Protocol/Internet Protocol (TCP/IP). Server based systems uses SMTP to send and receive e-mail. In addition, POP3 clients use SMTP to send e-mail over the Internet.

The advantages of using an SMTP-based mail server include:

• Server-based rules, which dictate how a message is handled when the server receives it.
• Multiple mail accounts so that each employee can have their own e-mail account.
• Messages are stored on the server rather than on the individual client computers.